#include <stdio.h>

enum interface {
    MAIN_INTERFACE = 0
};

static int main_interface(void);
typedef int (*interface)(void);

int main(void)
{
    interface p_interface[1];
    p_interface[MAIN_INTERFACE] = main_interface;

    p_interface[MAIN_INTERFACE]();

    return 0;
}

static int main_interface(void)
{
    printf("hello_world\n");
    return 0;
}